In recent years, it has become common practice to construct new houses with built-in vacuum systems which are used to clean the floors, carpets, drapes, upholstery, etc. in the house. Inlet valves are located in the walls or floors in each location and are connected by vacuum pipes positioned to a central vacuum drawing canister which is powered with one or more suction motors. The canister is usually located in the garage or basement of the house. A long hose and cleaning attachment are carried by the person who is cleaning the house and is fitted into the inlet valve closest to the room to be cleaned. The vacuum system is turned on by placing the hose end into the inlet valve and the carpet and floors in the room are then vacuumed. The dust and dirt collected by the vacuum cleaning attachment is drawn by vacuum to the central canister by way of the piping and is filtered from the vacuum air stream by one or more filters contained in the canister. In present built-in vacuum systems, the filtering action is usually achieved by means of a cloth bag suspended in the canister. Positioned within the cloth bag there is usually a removable disposable internal paper bag. Other filtering mediums may be located between the bag and the motor(s) used to draw a vacuum by means of powered vacuum fans. One is an inexpensive poly foam filter. This filter is sometimes held suspended between the bags and the motors by layers of glued grass or straw. This construction of filter, while inexpensive, is not particularly durable or efficient.
The applicant is aware of a number of built-in vacuum systems which are available on the market. One system is manufactured by Husky Industries Ltd. and marketed under the number model G250. Another system is manufactured by Sequoia Vacuum Systems, Inc., Menlow Park, Calif. A widely selling system is manufactured by MD Manufacturing Company, Calif.
The built-in vacuum systems built by these companies suffer from one or more shortcomings. One system (Husky Industries Ltd.) utilizes only one motor for drawing the vacuum. Thus total drawing power is limited. All of the three identified systems lose vacuum cleaning capability as dust and lint levels build up in the canister. All of the identified systems are limited in the maximum vacuum they are capable of drawing (usually about 3 ins Hg) and hence are not as efficient as they could be. All of the identified systems have rather poorly fitting attachments and fittings, which cause leaks and vacuum levels to be lost throughout the system.